Mini Progress Check – Self, Peer or Teacher Assess
Name:
Score/Grade:
The Nuclear Atom - Review Questions 23 marks
I think/reply.....
1)
Describe briefly one scattering experiment to investigate the size of the
nucleus of the atom.
Include a description of the properties of the incident radiation which makes it
suitable for this experiment.
In your answer, you should make clear how evidence for the size of the nucleus
follows from your description.
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[Total 8 marks]
Mr Powell 2013
1
Mini Progress Check – Self, Peer or Teacher Assess
2) Explain what is meant by the statement that the strong interaction is a short-range force
and explain what this implies about the densities of nuclei of various sizes.
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[Total 3 marks]
3) A uranium-236 nucleus,
, and tellurium-131,
(a)
236
92 U ,
131
52 Te .
undergoes fission, producing nuclei of zirconium-100,
100
40
Zr
Write a nuclear equation to represent this fission reaction.
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[1]
(b)
Each of the product nuclei is a – emitter.
(i)
State the change, if any, in the nucleon number and the proton number
caused by a – emission.
nucleon number ....................................................................................
proton number ......................................................................................
[1]
(ii)
The – decay of zirconium-100 is followed by three more – decays before
the product nucleus is stable.
State the nucleon number and the proton number of the resulting stable
nucleus.
nucleon number ....................................................................................
proton number ......................................................................................
[1]
Mr Powell 2013
2
Mini Progress Check – Self, Peer or Teacher Assess
3) Cont.. (iii)
On the figure below, use crosses to represent each of the nuclei
involved in the series of decays by which zirconium-100 changes to a stable nucleus.
Add arrows to show the direction of each reaction.
62
60
58
neutron
number
56
54
52
50
38
40
42
44
46
48
50
proton number
[2]
(iv)
On a graph of neutron number against proton number, stable nuclei all lie
close to a line. On the figure above, sketch this line.
[1]
Mr Powell 2013
3
Mini Progress Check – Self, Peer or Teacher Assess
(3) c) Zirconium-100 decays initially to niobium-100.
data:
(i)
nuclear masses:
zirconium-100
niobium-100
electron mass
99.895 808 u
99.891 679 u
0.000 549 u
Calculate the mass defect for this decay reaction.
mass defect = ...................................................... u
[2]
(ii)
Show that this mass defect is equivalent to about 5 × 10–13 J.
[2]
(iii)
When a particular zirconium-100 nucleus decays, the emitted – particle has
only about 2 × 10–13 J. Suggest why this is less than the energy calculated in
(ii).
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[Total 12 marks)
Mr Powell 2013
4
Mini Progress Check – Self, Peer or Teacher Assess
Answers
1) Any seven from:
α - particle scattering
suitable diagram with source, foil, moveable detector
2 or more trajectories shown
vacuum
most particles have little if any deflection
large deflection of very few
reference to Coulomb’s law /elastic scattering
alphas repelled by nucleus (positive charges)
monoenergetic
OR electron scattering
High energy diagram with source sample, moveable detector / film
Vacuum
Electron accelerator or other detail
Most have zero deflection
Characteristic angular distribution with minimum
Minimum not zero
De Broglie wavelength
Wavelength comparable to nuclear size hence high energy
B1 × 7
Clearly shows how evidence for the size of the nucleus follows from
what is described. (1)
[8]
2)
acts only on nearest neighbour / when nuclei are 1 diameter apart; (1)
either
so force holding nucleons/ neutrons together independent of size of nucleus (1)
or
reference to b so distance apart (of nucleons) must be constant;
so density of nucleus is independent of size; (1)
3
[3]
Mr Powell 2013
5
Mini Progress Check – Self, Peer or Teacher Assess
#3) (a)
(b)
(c)
236 U → 100 Zr + 131 Te + 51 n (1)
92
40
52
0
(i)
nucleon number: no change
proton number: increases by (1)
1
1
(ii) nucleon number: 100
proton number: 44 (1)
1
(iii) 5 correct points (1)
4 correct arrows (1)
2
(iv) straight line through / close to 56 / 44 of (1) ≤ gradient < 2
if curved, correct sense (1)
1
(i)
reactant mass = 99.895 808 u
product mass = 99.891 679 + 0.000 549 (= 99.892 228 u) (1)
mass defect = 0.003 580 u (1)
2
(ii) Δm = 0.003 580 × 1.66 × 10–27 (= 5.943 × 10–30 kg) (1)
E = (Δ)m c2
= 5.943 × 10–30 × (3.0 × 108)2 (= 5.35 × 10–13 J) (1)
2
or uses 1 u = 931 MeV so 0.00358 = 931 × 0.00358 (= 3.33 MeV) (1)
= 3.33 × 1.6 × 10–13 (= 5.33 × 10–12 J) (1)
(iii) (anti-)neutrino is also emitted (1)
(anti-)neutrino has (some) energy (1)
recoiling (niobium) nucleus has (kinetic) energy (1)
any 2
2
[12]
Mr Powell 2013
6